From: Dave Aronson Date: 2013-08-03T05:14:18+09:00 Subject: Re: How to use not equal and or On Fri, Aug 2, 2013 at 2:55 PM, Jesus Avila wrote: > ingresa = gets.chomp > ingresa = ingresa.downcase BTW, a tip: you can combine these two as "ingresa = gets.chomp.downcase". :-) > if ingresa !="sum"||ingresa !="sub"||ingresa !="mul"||ingresa !="div" Close! Sounds it out in English. "If it's not sum, or it's not sub, or it's not mul, or it's not div". Or in my probably-bad Spanish (which I'm guessing might be your first language), "Si no esta sum, o no esta sub, o no esta mul, o no esta div". Doesn't that just sound logically wrong to you, even in human-language? Now, think about what small change would make the logic correct, in human-language. Or, just how you would say it, in human. Then make that change in Ruby. Alternately, you could do something like "if it's sum, add them, else if it's sub, subtract, else if it's mul, multiply, else if it's div, divide, else complain". You could do that with an if-elsif-else chain, or a case statement, which is a very common way of acting on one of several options. Lastly, another general tip: your code would be more legible, and possibly easier for you to edit, with spaces in it, like so: if ingresa != "sum" || ingresa != "sub" || ingresa != "mul" || ingresa != "div" -Dave -- Dave Aronson, the T. Rex of Codosaurus LLC, secret-cleared freelance software developer taking contracts in or near NoVa or remote. See information at http://www.Codosaur.us/.